The enlarged gap after a cleaning is caused by the accumulation of too much calculus. Usually, if the patient finds it unsightly, it can be restored with resin. If the gap is more obvious and there is no way to get too good a result through resin restoration, gum thickening or periodontal tunneling techniques can also be used to achieve an aesthetic restoration, but only for a small amount of patients with gum recession and large gaps, and will not solve the situation of alveolar bone loss. If the periodontitis is severe, the cleaning or periodontal treatment will lead to a larger gap and even the possibility of a black triangle. However, the recovery of the lost alveolar bone through later bone augmentation restoration is also smaller and more expensive and disproportionate, and patients are advised to take local resin filling or gum thickening.